EReturn

The main idea behind this simple API is providing safe function result.

Usage

Every Function should yields a value with type return:result/0:

-type result() :: ok() | ok_result() | error().
-type  ok() :: 'ok'.
-type  ok_result() :: {'ok', term()}.
-type  error() :: {'error', {reason(), error_parameters()}}.
-type   reason() :: atom().
-type   error_parameters() :: [] | [error_parameter()].
-type    error_parameter() :: {atom(), term()}.

Example

Suppose i have a module named api.erl:

-module(api).
-export([func_1/0
        ,func_2/0
        ,func_3/0
        ,func_4/1
        ,func_5/1]).

%% Include return's header file and use its macros:
-include("/path/to/return/include/return.hrl").

-spec func_1() -> return:ok().
func_1() ->
    ...
    ?ok. %% means 'ok'

-spec func_2() -> return:ok_result().
func_2() ->
    ...
    ?ok(foo). %% {'ok', foo}

-spec func_3() -> return:ok() | return:error().
func_3() ->
    case ... of
        true ->
            ?ok;
        false ->
            ?err(reason_of_error) %% {'error', {reason_of_error, []}}
    end.

-spec func_4(term()) -> return:ok_result() | return:error().
func_4(Arg) ->
    case ... of
        Value when ... ->
            ?ok(Value); %% {'ok', Value}
        _ ->
            ?err(reason_of_error, [{argument, Arg}]) 
            %% {'error', {reason_of_error, [{argument, Arg}]}}
    end.

-spec func_5(term()) -> return:result().
func_5(Arg) ->
    try ... of
        Value when ... ->
            ?ok(Value);
        _ ->
            ?ok
    catch
        _:Reason ->
            ?err(crash, [{reason, Reason}, ?stacktrace, ?module, ?function, {arguments, [Arg]}]) 
            %% {error, {crash, [{reason, Reason}
            %%                 ,{stacktrace, erlang:get_stacktrace()}
            %%                 ,{module, ?MODULE}
            %%                 ,{function, ?FUNCTION_NAME}
            %%                 ,{arguments, [Arg]}]}}
    end.

Note that reason()must be atom() and error_parameters()must be a proplist, otherwise it exits with reason like {parameter_type, ...}.

Hex

18.6.5